Paul W
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 posted on 17/6/09 at 10:24 PM |
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R1 carbs on Sierra Dohc 8v
my kit is a part built GBS Zero, its got a 2 litre dohc 8v EFI (efi is missing) with standard ecu etc from a sierra.
I have a set of R1 carbs (spaced and setup for this engine) with alloy manifold but I dont have clue how to fit them
Where do fuel lines, vacuum and electrics go?
Do I need a fuel return to tank?
Do carbs need to be at an angle?
Can I use them with the original ecu without using Megajolt etc?(no money left)
Is there anyone out there that can help !!!!!
Please!!!!!!!!!!!!
Cheers Paul
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omega0684
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| posted on 17/6/09 at 10:42 PM |
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personally mate i would just ditch the DOHC! and go for something else that is alot more tunable! x-flows and zetecs have the exhaust on the sameside
as DOHC iirc. (if your side panels are already on)
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Paul W
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| posted on 17/6/09 at 11:04 PM |
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I know the dohc 8v isnt the best engine to use but lack of funds means I need to use the parts I hav.
I want to get the kit running IVA`d and on the road then hopefully I can do some upgrades
Cheers
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MikeRJ
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| posted on 18/6/09 at 07:12 AM |
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You shouldn't need a fuel return, but you should be using the correct fuel pump that goes with them; bike carbs are quite fussy about fuel
pressure.
The carbs should be used as close to the same orientation as they are on the bike as possible. The join between the float chambers and main body is
usually horizontal.
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r1_pete
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| posted on 18/6/09 at 07:14 AM |
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No fuel return is needed to the tank, but you CANNOT use the sierra injection pump, you must use a low pressure 1.5 psi ish pump designed for carbs,
preferably a bike carb pump.
There are no electrics to the carbs, unless you are using a TPS.
Vacuum, you will need to add take offs to each manifold runner, then feed each one to a smoothing vessel then on to the ignition advance/retard.
I have no idea whether you could mod the ecu to work, there were carbed DOHC engines which had a different ignition module, I have one kicking around
somewhere, you'll need to study the wiring diagrams to work out if you can mod it.
MJLJ would be easier, and better, but as Omega said, the engine really isn't worth it, for the cost of the trigger wheel and associated parts
you could get a 1.8 Zetec with the trigger system built in.
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bbwales
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| posted on 18/6/09 at 07:38 AM |
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Hi,
I have the same configuration and have found the engine to be very good for my application, I do have Megajolt though and you do not need a trigger
wheel as the engine has one built into the flywheel, just use the original sender for the MJLJ.
I made my manifold from the original as there is a problem with the thermostadt housing being part of the manifold.
I used a R1 fuel pump, which cost all of £5 from a scrappy.
You will only need a vacuum take off if you are using a servo, unless of course you use MAP version of MJLJ.
the angle that I fitted my carbs at was near enough 45 degrees thus making sure that the float chambers were horizontal.
I know you say you dont have any money left but a MJLJ kit was £45 and didnt take a great deal to build it, but I found it to be the way forward.
Hope that helps.
Regards
Bob
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Paul W
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| posted on 18/6/09 at 03:35 PM |
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Hi Bob
Its good to see someone else have faith in the DOHC.
The manifold I have has the thermo housing built in.
I m not using a servo.
My R1 carbs have a TPS on.
I have looked down the back of the sofa and found a few quid so it looks like I will get a Megajolt.
Are there different models of Megajolt?
Iam going to Newark Show on saturday would I be able to buy one there?
Are u goin with your locost ?
You have been a big big help
Cheers Paul
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